1. Field of the Invention
The present invention relates to an apparatus for adjusting a diameter of a folding drum the folding drum being capable of stably discharging sheets of paper during the operation of a folding machine in a rotary press.
2. Description of the Prior Art
A conventional technique will be explained with reference to FIGS. 4 through 6.
The operation of a folding machine is typically classified into single-folding and double-folding. The single-folding process is performed in the following manner. Sheets of printed paper which have been wound up are cut to a predetermined length by a saw blade 02a of a saw drum 02 in cooperation with a needle 03a of a needle device 03 of a folding drum 01. Subsequently the sheets of paper are creased by a folding blade 04 and are folded sheet by sheet by a pair of folding rollers 05. The paper is then discharged. On the other hand, the double-folding process is effected in such a way that the cut paper is made to pass temporarily by, halting the operation, a subsequent printed paper so folded so as to be superposed on the previous paper one, and the paper then being discharged.
A single unit of a folding machine serves to perform both the single-folding process and the double-folding process. The folding machine is constructed to adapt to a wide variety of modes, i.e., variations in the number of pages and the quality of paper. More specifically, as illustrated in FIG. 5, bands 06 are disposed respectively at three positions on the outer periphery of the folding drum 01. One end of each individual band 06 is so fixed as to be finely adjustable, and the other end thereof is movable in the tangential direction of the folding drum.
The band 06 is pushed from a position depicted with a solid line in FIG. 5 to a position shown by a dotted line on the the outer periphery of the folding drum 01, whereby the band 06 is swollen in the position 06a indicated by the dotted line. The overall diameter of the folding drum is adjusted on the basis of the quantity of swelling at the three positions on the outer periphery of the folding drum.
Mechanisms for adjusting the swelling quantity of the bands 06 at the three positions on the outer periphery will now be described. The adjusting mechanisms provided at the three positions have the same features, and hence only one of them will be explained.
The arrangement begins with a step of embedding one end of the band in the outer peripheral portion of the folding drum. One end thereof is connected with a pin 09a to a slide plate 07 slidable in the tangential direction for 0-point-setting by use of an adjustment screw 09c. The other end of the band is connected with a pin 09b to a slide plate 08 embedded in a position relative to the slide plate 07 on the outer periphery of the folding drum and slidable in the tangential direction. A rotatable cam follower 010 is fastened to the lower surface of the slide plate 08. The cam follower 010 is inserted in an oblique groove 012 chased in a portion of the upper surface of slide base 011 axially slidable by dint of a rotation screw rod 013. Note that the bands 06 are allocated to a plurality of positions in the longitudinal (axial) direction, and the plurality of slide plates 07 and 08 are set to be slidable with the help of guide plates 023a and 023b only in the direction axially orthogonal to the folding drum 01.
An operating end of the slide base 011 is formed with an internal thread. A screw rod 013, the opposite end of which is provided with a gear 014, is fitted into the internal thread. The screw rods 013 are axially rotatably supported on bearings 01b provided at the three positions on the outer periphery of the folding drum body 01. The gears 014 provided at the axial ends of the screw rods 013 mesh with gears 015 rotatably mounted on studs 015a embedded in the outer periphery of the folding drum body 01. Sprockets 016, integral with the gears 015, are linked through endless chains 021 to main driving sprockets 017 disposed at predetermined positions on the outer periphery of the folding drum. The endless chains 021 are, as depicted in FIG. 6(a), arranged so that their tensions are adjusted by idler sprockets 022 provided at predetermined positions on the outer periphery of the folding drum body 01.
The main driving sprocket 017 is fixed to an axial end of a wheel shaft 019 of a worm gear box 018 installed on the outer peripheral portion of the folding drum. An unillustrated handle is inserted from outside of the folding drum in the direction orthogonal to the drum into a four-side chamfering portion 020a provided at the axial end of a worm shaft 020 disposed orthogonally to the wheel shaft 019. The worm shaft 020 is manually rotated.
In this arrangement, the adjustment of the diameter of the folding drum involves the steps of stopping the machine, inserting the handle into the worm shaft end portion 020a of the worm gear box 018 provided on the outer periphey of the folding drum 01 and manually rotating the worm shaft 020. As a result, the rotation is conveyed to the gear 014 fixed to the axial end of the screw rod 013 through the sprockets 016 formed with the gears 015 which are provided at the three positions on the outer periphery of the folding drum by means of the endless chains 021, with the sprockets 017 serving as driving sources. The rotation of the gear 014 permits the slide base 011 to slide in the longitudinal direction of the folding drum through the screw rod 013, with the result that the slide plates 08 allocated to the respective positions of the folding drum direction simultaneously slide in the tangential direction through the cam followers 010. Because of the sliding action of the slide plates, the plurality of bands 06 connected through the pins 09b to the slide plates 08 concurrently expand and contract in the tangential direction of the folding drum at the three predetermined positions on the outer periphery of the folding drum, wherein the band connecting pins 09a of the slide plates 07 serve as cardinal points. The expansion and contraction of the respective bands are effected en bloc by manually operating the worm shafts 020, and their swelling quantities .beta. are controlled, thus adjusting the diameter of the folding drum.
In recent years, there has increasingly been a market-demand for a folding machine capable of responding to a wide variety of modes, viz., variations in the number of pages or in paper quality during operation. There arise, however, the following problems inherent in the prior art folding machine. Every time the diameter of the folding drum is adjusted to meet such requirements, the adjustment operations have to be done during the stoppage of machine. This results in poor performance. Besides, it is impossible to adjust the diameter of the folding drum while observing conditions under which the sheets of paper are drawn in during the operation. Therefore, the market needs of automatization and presetting of the folding machine can not be attained.